Does method already exist in ActionScript to search array and return first index whose element is > some #?

Question

Using ActionScript 3, suppose I have an array of numbers, lets say: 1, 2, 3, 4, 5. Is there a way to easily search this array and return the index corresponding to an element that is >= 2.5 (which would be, 3, in this case), for example? I'm implementing this with a while and for loop, and seems pretty wordy. Thought there might be a method for this already, but haven't stumbled upon it in:

http://help.adobe.com/en_US/FlashPlatform/reference/actionscript/3/Array.html#every()

Otherwise, what would be a simple way to achieve it?

In case it helps, I'll use this to implement a straight-forward linear interpolation math routine, assuming one doesn't already exist I'm not aware of.

Jason Sturges · Accepted Answer · 2011-11-16 01:03:07Z

3

I'm not aware of any firstIndexOf in ActionScript.

You could add it to an ArrayUtil class:

Given the array:

var array:Array = [ 1, 2, 3, 4, 5 ];

Pass it to the ArrayUtil function:

public static function firstIndexOf(array:Array, value:Number):int
{
    for(var i:uint = 0; i < array.length; i++)
    {
        if(array[i] >= value)
            return i;
    }

    // if not found, return -1
    return -1;
}

edited Nov 16, 2011 at 1:03

answered Nov 16, 2011 at 0:49

Jason Sturges

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4 Comments

Jason Sturges Over a year ago

Oops - I forgot to add a -1 return in case no value was greater in the set. Maybe this should be named differently as well - firstIndexGreaterThan(...)

ggkmath Over a year ago

For completeness, I think the for loop assignment should extend to (array.length-1) since indexing begins at 0.

LoremIpsum Over a year ago

i < array.length will stop at array.length - 1.

ggkmath Over a year ago

Oops, my mistake (I always use <= in my expressions!).

Marty · Accepted Answer · 2011-11-16 00:48:38Z

0

var t:Array = [4,9,1,2,3,5,6];

function something(base:Number, array:Array):int
{
    var t:Array = array.slice();
    var h:Number = int.MAX_VALUE;
    var i:int = -1;

    while(t.length > 0)
    {
        var l:Number = t.pop();

        if(l >= base)
        {
            if(h > l)
            {
                h = l;
                i = t.length;
            }
        }
    }

    return i;
}

trace(something(2, t)); // at index [3]

answered Nov 16, 2011 at 0:48

Marty

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2 Comments

ggkmath Over a year ago

Thanks Marty, I hadn't thought of using pop like this.

Marty Over a year ago

Unless your arrays are ridiculously massive and/or this is being run very frequently, I don't think you will run into any troubles.

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